It is known that a photographic image of very high contrast can be formed using a certain type of silver halide. Methods for forming such a photographic image are known in the field of photomechanical processes.
For example, a method is known for obtaining a line original or a dot image having an image part and a non-image part distinguished clearly and having a high contrast and a high optical density, which method comprises treating a lith type silver halide photographic material comprising silver chlorobromide (containing at least 50 mol % of silver chloride) with a hydroquinone developing solution having a very low effective concentration, usually 0.1 mol/l or less, of sulfite ions. However, the sulfite concentration in the developing solution of the method is so low that the quality of the image formed by development with the developing solution is very unreliable due to air oxidation, so that at present various endeavors are being undertaken in an effort to stabilize the activity of the developing solution.
Therefore, an image-forming system has been demanded which can alleviate the defect of unreliable image formation inherent in such a development method (lith development system) as mentioned above, and which can provide superhigh contrast photographic characteristics through development with a processing solution having good storage stability. As disclosed in U.S. Pat. Nos. 4,166,742, 4,168,977, 4,221,857, 4,224,401, 4,243,739, 4,272,606, and 4,311,781, there have been proposed systems to form superhigh contrast negative images having a Y value exceeding 10 by treating a surface latent image-type silver halide photographic material containing a specified acylhydrazine compound with a developing solution having a pH value of 11.0-12.3, said developing solution containing a sulfite preservative at a concentration of 0.15 mol/l or more; and having good storage stability.
However, the new image-forming system has defects. For example, when a large number of films are treated, the sensitivity, .gamma., or the maximum density of photographic material is lowered because the pH value of developing solution is reduced or bromine ions in the developing solution are increased. Further, the system also has such defects that, if the concentration of sulfite as a preservative in the developing solution is markedly decreased or the pH value of developing solution is increased because of fatigue of the developing solution with passage of time while a small number of films are treated with the developing solution, many black peppers are formed and, at the same time, the maximum density is reduced. To alleviate these defects, a method to increase the amount of replenisher for the developing solution can be adopted. The method, however, has problems such as an increase in cost, a waste solution, and the like. A system free from a fluctuation in sensitivity, a lowering of D.sub.max, and formation of black peppers without the necessity of increased amount of replenisher has been demanded strongly.